Parcel2 + mobx-react-lite:3.1.5, invalid production build output

[evilfer]

Hi,

I have a project using Parcel2+react+typescript+mobx, and builds were fine with mobx-react:7.0.0 (and dependency mobx-react-lite:3.0.1).

However, after upgrading to mobs-react:7.0.4 and mobx-react-lite:3.1.5, production builds contain what looks like invalid JS output.

As an example, I created this repository: https://github.com/evilfer/mobx-react-lite-test-build.

In there, https://github.com/evilfer/mobx-react-lite-test-build/blob/master/dist-mf704-mrl315/mrl.a6b78398.js is the JS output with mobs-react:7.0.4 and mobx-react-lite:3.1.5. The output includes in four places this code: {}() which fails to run with error "{} is not a function".

The same project build with versions mobx-react:7.0.0 and mobx-react-lite:3.0.1 has correct output https://github.com/evilfer/mobx-react-lite-test-build/blob/master/dist-mr700-mrl301/mrl.5d4eb783.js, without any case of {}().

I believe the way the {}() bits are generated are:

• mobx-react does:

import { isUsingStaticRendering } from "mobx-react-lite"
...

isUsingStaticRendering()
...

• Somehow the import doesn't work as expected, and isUsingStaticRendering ends up being {} in the compiled code.

• The reason is probably related to a change in the export in mobx-react-lite:

  • new (fails): Object.defineProperty(exports, "isUsingStaticRendering"
  • old (works): exports.isUsingStaticRendering = staticRendering_2.isUsingStaticRendering;

I know the change that causes the issue is not in Parcel, but I wonder whether Parcel should be able to work with the updated version.

(Note: ticket in the mobx repo: mobxjs/mobx#2609 (comment))